The present invention relates to a method for the control of an iron-ore agglomeration process on the basis of a couple constituted by the values: permeability of the mixture of materials to be agglomerated, and quantity of water to be added to the mixture.
The manufacture of agglomerates includes initially making up a mixture of ores, combustible solids (for example coke), return fines, and various additions (for example fluxes). The mixture is then introduced into one or more appliances generally referred to as mixers where there is effected the addition of water with a view to achieving the requisite permeability. The mixture is then fed towards the agglomeration apparatus, e.g. a sinter strand.
The importance of the gas permeability of the mixture is well known and regulation methods have been proposed in which the permeability is measured and comparison is made between the measured value and a predetermined set value considered as ideal. If the measured value deviates from the set value, the quantity of water added to the mixture is modified so as to suppress this deviation with the least delay.
The permeability is measured by means of an appliance referred to as a "permeameter" in the present specification. The principle of this measurement is known and one of the inventors in this connection has specifically considered a novel application intended to give the measurement sufficient sensitivity (U.S. Pat. No. 3,505,856).
These modes of regulation have given very satisfactory results since they have enabled the permeability to be stabilized at values close to the set values.
In all known cases the appliance for the measurement of the permeability is always situated downstream of the mixer, which itself directly precedes the feed hopper for the agglomerating apparatus. Because of this, between the instant of the measurement of the permeability and the instant of the addition of the water there is a dead time during which the mixture is not subject to any correction and in consequence of which it can present undesirable variations of permeability.